Paul: I tried slaked lime on some of our high FFA crude palm oil and had similar results to Keith. Leaving it overnight to settle gave me only about 15% recovery of the oil.
Part of the problem is the very high viscosity of our CPO which is rather like mayonnaise even at 30 degC. Things just don't settle in this goo unless you heat the brew. Terry's suggestion of quicklime has some merit because it takes the water out of the gloop as it esterifies the FFA but it still has such a low density that it doesn't settle for us. We probably need barium oxide or maybe something made from spent nuclear fuel rods! Keith: For the same reason, we find your cold NaOH treatment won't work for us. In fact our yellowy-orange mayonnaise turns into engine grease when we mix in the NaOH solution at 30 degC. Mind you, this crude palm oil (CPO) titrates at 18.5 ml 0.025M NaOH/(ml of oil)and contains MANY STRANGE THINGS from the palm-nut kernel oil also in there. (I shouldn't be surprised if it is quietly polymerising!) Right now I am holding a litre of it (treated with 18.5 gms of NaOH dissolved in 10 mls of water) at 80 degC in the oven just to see if anything settles out overnight. Regards Michael Allen Thailand --- Keith Addison <[EMAIL PROTECTED]> wrote: > Hello again Paul > > I tried slaked lime to remove FFAs as you suggested. > The filtering is > a pain, and the result wasn't very good. It did take > out some FFA, > but it didn't neutralize the oil, though I used an > excess. I didn't > titrate it afterwards, maybe I should have, but that > would have been > yet another step, and I think I'd have been > titrating residual lime > as much as anything. Unless I'd washed it out, which > might not have > been too effective, and yet another step. Whatever, > it didn't reduce > the FFA sufficiently - I tried to transesterify it > with the basic > amount of lye, 3.5 gm/litre, but it wasn't nearly > enough. I didn't > continue with it after that to find out how much > would have been > enough, didn't seem to be any point, but I reckon it > would have > needed twice that much or more. > > The caustic refining step is much simpler - no > heating, no filtering, > nothing extra - and it works well. Also I reckon the > soapstock is > useful, but I don't think the deposit the lime > leaves you with is > useful. I fine-tuned the caustic refining step a bit > and got 80% > production from oil titrating at 9.15 ml. I can only > get 75% > production from that oil with a single-stage base > process, and this > is much easier. It's a lot quicker and simpler than > acid-base - > though again acid-base gives higher production and > uses less lye. But > lye's cheap, and 80% is okay for dirty oil like > this. > > Terry suggested CaO, quicklime, which is not easy to > come by these > days, though I do have some. Maybe I'll give it a > try. But actually > I'm quite satisfied with this caustic refining step > - what Michael > more correctly called > saponification-transesterification. Definitely > preferable to single-stage base for high-FFA oils, > and a useful > alternative to acid-base. > > Best wishes > > Keith > > > > >Hello Paul > > > > >----- Original Message ----- > > >From: Keith Addison <[EMAIL PROTECTED]> > > >To: <biofuel@yahoogroups.com> > > >Subject: [biofuels-biz] High FFA oils - another > way > > ><snip> > > > > > > > I found an easier way though: two-stage > base-base, only the first > > > > stage doesn't use methanol, it uses (horror!) > water. > > > > > > > > Mix the titration amount of NaOH, in this case > 9.15 grams per litre > > > > of oil, with 40 ml of water per litre of oil. > > > > > > > > Add the dissolved NaOH to the oil (room > temperature), stir gently by > > > > hand until thoroughly mixed. > > > > > > > > Settle overnight. This leaves soapstock at the > bottom and some gunk > > > > floating on the top. The water is apparently > in the soapstock. > > > > > > > > Filter to remove soapstock and gunk - no need > for fine filtering, > > > > fine steel mesh will do (like a fine tea > strainer). > > > > > > > > Now process as usual for virgin oil - 3.5 > grams NaOH per litre of > > > > oil, 20% methanol, 55 deg C, good and > prolonged agitation as usual. > > > > > > > > Good product, production rate in this case > 73%, slightly less than a > > > > normal single-stage, but it's a much easier > process that won't go > > > > wrong, and it's nice not to have to make such > strong methoxide as a > > > > straight single-stage process would require > with this oil, 13.65 > > > > grams of lye per litre oil, or more like 14 > grams (needs a bit of > > > > excess lye). > > ><snip> > > > > > >Slaked lime (CaOH2)can also be used to remove the > FFA from WVO or high FFA > > >biodiesel rescued from overuse of NaOH (gel) with > acetic acid. > > > >You settle it with acetic acid? I think the > resultant FFAs just > >dissolve back into the biodiesel then. > > > > >Mix the lime into the WVO/BD and heat with > occasional stirring to 100 deg C. > > >The lime appears to dissolve in WVO as heated but > is probably just held in > > >suspension. > > >Cool decant and filter. No problems with ammount > of lime just use excess. > > > >Thanks Paul, I'll try that. But this caustic > refining step is so easy > >I'm quite satisfied with it, and there's no need > for heat, for > >filtering, or for anything you haven't already got. > > > >"... just use excess" - about how much per litre? > > > > >Would much rather go acid/base with feedstock > with FFA content this high, > > > >Sure, as I said, but a lot of people don't do > acid-base. Also, > >acid-base doesn't like this particular oil, it has > a lot of salt in > >it (tempura oil). Hot pre-washing solves that > problem, but that then > >makes the acid-base process a lot more trouble than > this, and a lot > >more energy use, so you're left to choose between > much more time and > >hassle for the acid-base advantages, or a quick and > easy way like > >this, and there's not much in it. Especially since > I think recovered > >FFAs are useful, not wastage. You're not using more > methanol, the > >extra lye isn't expensive, so it's really just some > extra phosphoric, > >no big deal, as against no sulphuric. > > > > >less wastage/recovery > > > >"It's an alternative - better than straight > single-stage base for oil > >like this, and while it won't get as a high a > production rate as > >acid-base, and it uses more catalyst and gives you > more co-products, > >it's very quick and simple, and the product is > good." > > > > >and acid stage allows alcohols other than > methanol or > > >ethanol to be used. Isopropanol for instance has > the potential to reduce > > >cloudpoint. > > > >Have you tried the acid-base process with > isopropynol? That'll make > >branched alkyl esters, low cloud-point yes, but I > don't know of > >anyone that's had any success with isopropynol or > butyl other than > >with enzymes, though I do know people who've tried. > Reference > >previously posted in "Cracking" thread, Foglia et > al, for instance. > >Pressure maybe. > > > >Best wishes > > > >Keith > > > > > > > > > >Regards, Paul Gobert > > __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com ------------------------ Yahoo! Groups Sponsor ---------------------~--> Plan to Sell a Home? http://us.click.yahoo.com/J2SnNA/y.lEAA/MVfIAA/9bTolB/TM ---------------------------------------------------------------------~-> Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://www.webconx.dns2go.com/2000/biofuel/biofuel.htm List messages are archived at the Info-Archive at NNYTech: http://archive.nnytech.net/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
